1. Field of the Invention
This invention broadly relates to systems and processes for testing electrodynamic equipment such as electrical generators. More specifically, this invention relates to an improved carriage for performing such testing.
2. Description of the Prior Art
Westinghouse Electric Corporation, the assignee of this invention, has developed several remotely controlled carriages that will go into the air gap of an electrical generator to perform various inspections. Such inspections may include visual examinations of the generator stator and rotor, testing for electrical shorts in the stator core laminations, and testing the tightness of stator wedges in the stator slot. Such carriages are disclosed in U.S. Pat. Nos. 4,803,563, 4,962,660, 4,970,890, and 5,020,234.
Such inspection carriages are typically held against the stator iron by use of permanent magnets which are provided on the carriages. In many electrical generator designs, a gap is provided between the stator wedges and the stator iron, and this enables the carriages to be guided along the stator slots by use of thin guides that ride in the stator slot, which keeps the carriages from straying into another stator slot. However, some generator designs do not include such a gap. In those generators, it is difficult to accurately guide an inspection carriage along a stator slot which is to be inspected. If an inspection carriage becomes misaligned with respect to the stator slot, testing accuracy is often compromised.
In addition, inspection carriages typically are connected to a control unit by a control cable. In some situations, the weight of the control cable or other forces transmitted by the cable can interfere with movement of the carriage along the stator slot which is to be tested.
It is clear that there has existed a long and unfilled need in the prior art for a remotely controlled electrical generator testing carriage which can accurately traverse a stator slot without the use of a mechanical guide, and which is insulated from forces which are transmitted through the control cable.